Manufacturers of engines, transmissions and hydraulic devices have a need to test lubricating and hydraulic oils, in order to determine the flow and filterability characteristics of such oils as well as other parameters associated with the functional qualities, thereof. One way of so-testing these fluids is to use them in full size devices. However, for test purposes, this procedure is exceedingly expensive and requires an objectionably long period of time. In addition, when the oil to be tested is at a low temperature, it is necessary that the complete engine or vehicle be placed in a cold room and that the temperature be monitored over an extensive period of time in order to bring the lubricating oil to the required temperature of the test. In view of these disadvantages, it is desired to provide a relatively small, fast, simple-to-use laboratory apparatus wherein the oil can be rapidly tested under controlled conditions and with a high degree of correlation between the test results and the results that would be obtained when the oil is used in a full size device. Furthermore, it is desired that this apparatus be of a portable nature such that it can be readily transported to various locations in order to perform the test.
One attempt at providing a laboratory testing apparatus is disclosed in U.S. Pat. No. 3,872,710, entitled "Apparatus For Measuring the Index of Filterability of a Liquid". Structurally, this apparatus is different from the present invention in that it uses a regulating drum to supply fluid to a filter. The fluid, after passing through a filter, is routed to a reservoir or back into the regulating drum. There is no provision for creating a back pressure across the filter or for cooling the oil before it flows out of the regulating drum.
Now, an apparatus and method have been invented which will satisfy the present needs of the industry.